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Gamestation in need of repair & my progress (someone hel

 
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PostPosted: Tue Feb 25, 2014 7:13 pm    Post subject: Gamestation in need of repair & my progress (someone hel Reply with quote

Hi,

I have been trying to repair a Gamestation which yes, it is a SNES clone with an updated GDSF7 on a single small PCB attached to it and a CD-ROM drive resting on top which is only insulated away from the PCB by a small piece of hot glue and the plastic chassis it is fastened into (this is a very crude unit indeed).

With that out of the way, I have the circuit boards sitting here on a piece of plywood so I can work on it without the plastic chassis in the way, and using the top cover for the reset and power switches which work fine (measured continuity across those when they are in the "on" position and when they are "off", there's no continuity)

Ok so I went over all the components I could on this board, short of the ICs and found that everything appears to be alright, no open circuits, capacitors all appear to hold charge, no ballooned caps, the two voltage regulators appear to work, putting out about 10.5V and 5V on their terminals.

When I received this unit, the cases were not fastened and the cdrom was not completely screwed into the chassis. Also I found that the voltage regulator on the GDSF7 board had a broken leg and all 3 legs were shifted over to one side so they were very close but nearly and not touching.

I have checked out what all the ICs on this thing are for. Starting with the SNES clone, it has the same SNES clone chips that are used in the Tristar 64. There's 2 Winbond chips and one Toshiba chip that I have yet to identify but I don't believe there is a fault in the SNES clone circuit.

The reason why I don't think the SNES clone is faulty is because when I turn the unit on, while it does not display anything, it does put out "signal" to my TV set. Once I turn it off, no signal is present. So this leads me to believe that possibly the GDSF7 portion is in need of repair.

I have found on the GDSF7, there are a few RAM chips and possibly a large Actel Logic core that says Bung on it (I would assume that Bung bought some Actel chips and scrubbed off the logo to put their own on, I seriously doubt Bung was manufacturing this kind of chip)

Also I found two CMOS chips on the GDSF7 portion as well as one Hyundai EPLD (electrically programmable logic device) which leads me to further believe that quite possibly that chip is wiped and is the culprit, and needs to be replaced.

However I doubt that if I ask anyone on here for a dump of that chip, that it would surface. So if anyone else thinks something different is wrong with this unit, please share your input. Since this item is so scarce, I can't find any repair information whatsoever on a google search or on forums searches.

Also to note, this is yet another "core negative" 12V DC device. There's always the possibility on these that someone plugged in the polarity backwards and zapped the crap out of the chips inside but there is no burnt smell, no holes in the ICs or anything, though they really have little of anywhere to arc current to besides within themselves.

I think the only thing I can try replacing on this is the Sony chip but who knows if it even is a problem with the SNES clone itself. The SNES clone does not appear to have any polarity reversing protection circuit nor anything to prevent it from being overloaded. There are no fuses and on a real SNES deck, if the fuse is good quite often times the tri pole diode is bad. This device does not have a tri pole diode but it does have a few diodes and they all check out fine with a DMM.

Any help would be appreciated. At this point, I have exhausted all other resources so it is going to get boxed back up and shelved.

I also do have a dump of the GDSF7 7.20b bios that is in this unit. I used a genius programmer to dump it. It looks like it is probably ok but I have no way to compare it since the last person whom dumped it has disappeared from the internet.

Edit: this thing is dead. GDSF7 main chip is fried. It appears that everything else would work if that chip did.

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